.button {
  position: fixed;
  z-index: 99999;
  top: 50%;
  right: 0;
  transform: translateY(-50%);
  padding: 8px;
  border-radius: 5px 0 0 5px;
  writing-mode: vertical-rl;
  background: none;
  cursor: pointer;
  border: none;
  transition: all .3s ease;
  background-color: #1b66cc;
  color: white;
}

.button:hover {
  /* box-shadow: 0 0 10px 2px rgba(0, 0, 0, 0.15); */
  background-color: #3178db;
}